Table 14.

Studies of SPG radiofrequency ablation on head and facial pain

First author	Year	Medical problem	Approach	Imaging	Temperature (°C)	Type of RFA	How to identify the right spot	Study design	Number of cases	Outcome
Salar et al. [50]	1987	Sluder’s neuralgia	Lateral extraoral approach	Fluoroscopy	60 and 65	Continuous	0.2-0.3 V, paresthesia in the distribution of the maxillary nerve	Case series	7	Disappearance of the typical pain attacks, lacrimation and nasal secretion, however, a slight, deep-seated troublesome sensation persisted
Shah et al. [84]	2004	Posttraumatic headache	Infrazygomatic approach	Fluoroscopy	42	Pulsed	50 Hz and 0.5 V produced tingling sensation at the root of the nose	Case report	1	Pain reduced from 10/10 to 1/10
Bayer et al. [85]	2005	Chronic head and face pain	Infrazygomatic approach	Fluoroscopy	42	Pulsed	50 Hz up to 1 V, paresthesia elicited at the roof of the nose, motor stimulation performed at 2 Hz to rule out trigeminal contact, which results in rhythmic mandibular contraction	Case series	30	21% had complete pain relief, 65% had moderate pain relief, 14% had no pain relief.
Nguyen et al. [86]	2010	Atypical trigeminal neuralgia	Coronoid approach	Fluoroscopy	42	Pulsed	50 Hz with 1 ms pulse duration, 0.6 V	Case report	1	Symptom-free after 2 yrs.
Oomen et al. [79]	2012	Atypical facial pain, cluster headache, Sluder’s neuralgia, Sluder’s neuropathy	Infrazygomatic approach	Fluoroscopy	80	Unknown	50 Hz, paresthesia in the nose and not in the area of the maxillary nerve	Case series	4 atypical facial pain, 2 Sluder’s neuralgia, 2 Sluder’s neuropathy, 1 post-traumatic neuropathy of infraorbital nerve, 1 postherpetic neuralgia, 1 SUNCT	Adequate pain reduction: 4/4 in atypical facial pain, 2/3 in cluster headache, 1/2 in Sluder’s neuralgia, 2/2 in Sluder’s neuropathy, 1/1 in posttraumatic neuropathy, 0/1 in post-herpetic neuralgia, 0/1 in SUNCT (60% showed considerable pain relief after a single procedure).
Elahi et al. [87]	2014	Facial pain secondary to cavernous sinus meningioma removal	Infrazygomatic approach	Fluoroscopy	80	Continuous	50 Hz, paresthesia in the nasolabial midline region	Case report	1	Satisfactory pain relief at 12 months
Akbas et al. [40]	2016	Atypical facial pain, SPG neuralgia due to herpes zoster, atypical Trigeminal neuralgia	Infrazygomatic approach	Fluoroscopy	42	Continuous	Paresthesia at the roof of the nose at 0.5–0.7 V. To rule out trigeminal contact, motor stimulation at a frequency of 2 Hz was applied	Case series	27	Pain relief not achieved in 23%, completely relieved in 35% and moderately relieved in 42% of patients